Field of the Invention
The present invention relates to a flush toilet apparatus that washes a toilet body by wash water.
Description of the Related Art
Conventionally, a flush toilet apparatus using a tank-type or direct-pressure water supply mechanism is widely used as a mechanism for supplying wash water to a toilet body.
The tank-type water supply mechanism is configured to store water in a tank in advance and supply the water to a toilet body as wash water. In the tank-type water supply mechanism, all of the water supplied as wash water needs to be stored in the tank, and there is a problem that the tank mounted on the flush toilet apparatus is large.
After the completion of washing of the toilet body, the tank needs to be at a full water level for the next washing. However, it takes time to pour water into the large tank to reach the full water level. Therefore, continuous washing (at short intervals) is difficult, and there is a problem that the tank-type water supply mechanism is not suitable for a situation in which the flush toilet apparatus is frequently used.
The direct-pressure water supply mechanism is configured to use water pressure in a water supply pipe (water pipe) arranged in a building to supply wash water to the toilet body from the water supply pipe. In the direct-pressure water supply mechanism, the flow rate of the wash water depends on the water pressure in the water supply pipe. Therefore, there is a problem that the washing performance is reduced when the flush toilet apparatus is installed in an environment with low water pressure (for example, upper floors). Furthermore, the diameter of the water supply pipe connected to the flush toilet apparatus needs to be large to allow the direct-pressure water supply mechanism to supply a large amount of water. Therefore, there is a problem that large-scale construction is necessary.
A jet-pump water supply mechanism is newly proposed as a water supply mechanism that can simultaneously solve both of the problem in the tank-type water supply mechanism and the problem in the direct-pressure water supply mechanism (see Japanese Patent Laid-Open No. 2004-156382).
The jet-pump water supply mechanism described in Japanese Patent Laid-Open No. 2004-156382 includes a tank storing water, and a jet pump unit is submerged and arranged inside of the tank. The jet pump unit includes a throat pipe. One end of the throat pipe is connected to a channel toward a bowl portion of the toilet body, and an opening is formed on the other end. When water is injected from an injection nozzle toward the inside of the throat pipe through the opening, a jet pump action is induced, and a large amount of water flows toward the bowl portion inside of the throat pipe. Not only the water injected from the injection nozzle, but also the water stored in the tank is drawn in and flows inside of the throat pipe. Therefore, a large amount of wash water is supplied to the toilet body.
Not all of the water supplied as wash water to the toilet body needs to be stored in the tank in the jet-pump water supply mechanism. Therefore, the tank can be smaller than in the tank-type water supply mechanism, and there is an advantage that the time necessary for the tank to reach the full water level can be reduced. A large amount of wash water can be supplied to the toilet body even when the flush toilet apparatus is installed in an environment with relatively low water pressure in the water supply pipe. There is also an advantage that large-scale construction for enlarging the diameter of the water supply pipe is not necessary.
When the jet-pump water supply mechanism is mounted on the flush toilet apparatus, the flush toilet apparatus is unlikely to be affected by a change in the water pressure in the water pipe or a change in the water level (potential energy) in the tank, and a large amount of water is supplied at substantially a constant flow rate.
However, the present inventors have conducted intensive studies and found that the flow rate of the minimum wash water necessary to discharge waste is not always constant in the process of washing, and the minimum wash water changes with time. More specifically, it has become clear that part of the wash water may be wasted if the jet-pump water supply mechanism always supplies water at a constant flow rate.
In this way, the total amount of wash water supplied to the bowl portion can be reduced to further save water in the flush toilet apparatus provided with the jet-pump water supply mechanism.
The present invention has been made in view of the problems, and an object of the present invention is to provide a flush toilet apparatus that can reduce the total amount of wash water supplied to a bowl portion, even though a jet-pump water supply mechanism is mounted.